Angiography is a procedure used to specifically image, diagnose, and treat abnormalities in the heart or vascular structures. In recent decades, radiologists, cardiologists and vascular surgeons have also used angiography procedures to guide minimally invasive surgery of the blood vessels and arteries of the heart. During angiography, a physician inserts a catheter and injects a contrast material into a vein or artery of a patient. The vascular structures fluidly connected with the vein or artery in which the injection occurred are subsequently filled with the contrast material. Next, the area of the patient's body injected with the contrast material is imaged using x-ray energy, whereby the radiation beam passes through the tissue of the patient and is absorbed by the contrast material. The resulting image or radiographic outline of the blood vessel is recorded onto film or videotape and/or displayed on a fluoroscope monitor. The images can be used for many purposes, as for example diagnostics and interventional procedures such as angioplasty, wherein a balloon is inserted into a vascular system and inflated to open a stenosis.
Various manual and automated injection systems used for performing angiography procedures are known in the art. Most current systems include a syringe and other disposable components (such as manifold tubing, spikes, etc.) operatively connected to a catheter. The syringe is filled by creating a vacuum which causes the contrast media to be suctioned into the chamber of the syringe. Any residual air is ejected from the chamber before connecting the syringe to the patient catheter. Once the system is completely set-up and primed, the syringe is connected to the patient catheter and the contrast media is injected into the target area.
The volume and flow rates of contrast media injections vary depending on patient parameters (such as heart/chamber/vasculature size, patient weight and physical condition) and type of treatment or diagnosis performed. Due to the variability of these parameters, it is often difficult to calculate the precise amount of contrast media needed for a particular patient and procedure. As a result, there exists the potential that the syringe chamber will be either under-filled or over-filled for a particular patient and/or procedure.
If the chamber is under-filled, an insufficient volume of contrast media will be injected into the patient, resulting in a less than optimal image and requiring that the procedure be repeated. This is not only expensive due to the high cost of contrast media, but is also potentially harmful to the patient in view of the additional radiation exposure and contrast dose injected into the patient. Conversely, if the syringe is over-filled, there will be an excess volume of contrast media remaining in the syringe after completion of the imaging procedure. To avoid patient contamination and product adulteration, the remaining volume of contrast media is simply discarded. Although over-filling the syringe avoids the problem of having to repeat the imaging procedure, over-filling wastes contrast media which is costly to hospitals and health care facilities.
Typically, contrast media is supplied in fluid volume containers having a 50 ml, 100 ml, 250 ml or 500 ml capacity. In contrast, patient procedures characteristically require as little as tens of milliliters to as much as hundreds of milliliters of fluid per procedure. The limited container volumes in conjunction with the variability associated with patient procedures often result in wasted fluid. For example, if a procedure requires 150 ml of fluid and a 250 ml container is used, the amount of fluid remaining in the container at the end of the procedure is discarded due to possible cross-contamination and fluid-crystallization issues. The discarded, unused portion not only wastes fluid, but also significantly contributes to increased hospital costs.
In addition to cost issues, the medical community is also faced with contamination problems associated with imaging procedures and, more particularly, the injector systems used to dispense the fluids. For example, the syringe, tubing and ancillary injector components used during imaging procedures are in fluid-communication with the patient. As a result, these items must be discarded after each case in order to avoid patient and/or product contamination, a potential risk confronting all products used during invasive procedures. Another reason for disposing of these items after a single use is that the majority of the imaging components are made of materials that are incompatible with state-of-the-art cleaning and resterilization procedures and, therefore, cannot be reused.
Although presently available injector systems are well accepted by the medical profession and function as required, it is desirable to have a more cost-effective injector system that is also safe and efficacious to use. In particular, it is desirable to have an injector system with a reservoir of contrast media that allows more than one patient to be injected using the same reservoir supply. It is also preferred that the system accommodate a variety of reservoir/container designs and fluids having various volumes, concentrations, viscosities, etc. It is also essential that the contrast media/fluid supply remain contamination-free during each use. In addition, it is desirable to have an injection system with a variety of accessory components that are single use, multiple use and resterilizable. Further, it is preferred that the system perform both diagnostic and non-diagnostic procedures, such as x-ray procedures, CT scanning, magnetic resonance imaging, ultrasonic imaging, angioplasty, saline ablation, etc., and is capable of using a variety of fluids, such as contrast media, saline, flushing fluids, etc.